Electric switch

ABSTRACT

An electric switch in which a pair of blades having contacts thereon are mounted on a base. A bimetallic blade is also mounted on said base in engagement with one of said pair of blades to vary the position of their contacts with respect to each other in response to temperature changes. A sleeve adjustably carried in a rigid arm mounted on the base has a pin projecting therefrom for engagement with one of said pair of blades to vary the position of their contacts with respect to each other for controlling the temperature at which said bimetallic blade will effect contact opening and closing. Said pin is also movable with respect to the sleeve by a cam swingably mounted in said sleeve to vary the position of the contacts between an off position in which they are prevented from closing and an on position in which they are opened and closed under the action of the bimetallic blade.

United States Patent Inventor Amos E. Chesnut 1 Columbus, Ind. Appl. No.47,750 Filed June 19, 1970 Patented Nov. 2, 1971 Assignee ArvinIndustries, Inc.

Columbus, Ind.

ELECTRIC SWITCH 6 Claims, 4 Drawing Figs.

US. Cl. 337/375, 337/349, 337/361 Int. Cl H0lh 37/18 Field of Search337/67, 342, 349, 347, 360, 361, 368, 374, 375; 200/170; 219/515References Cited UNITED STATES PATENTS 2,741,682 4/1956 Schwaneke et a1.337/375 Wily/11 Primary Examiner-Bernard A. Gilheany AssistantExaminerF. E. Bell Attorney-Trask, Jenkins and Hanley ABSTRACT: Anelectric switch in which a pair of blades having contacts thereon aremounted on a base. A bimetallic blade is also mounted on said base inengagement with one of said pair of blades to vary the position of theircontacts with respect to each other in response to temperature changes.A sleeve adjustably carried in a rigid arm mounted on the base has a pinprojecting therefrom for engagement with one of said pair of blades tovary the position of their contacts with respect to each other forcontrolling the temperature at which said bimetallic blade will effectcontact opening and closing. Said pin is also movable with respect tothe sleeve by a cam swingably mounted in said sleeve to vary theposition of the contacts between an off position in which they areprevented from closing and an on position in which they are opened andclosed under the action ofthe bimetallic blade.

PATENTEDHM ml 3.617.973

118-3 AMOS E. CH

ELECTRIC SWITCH BACKGROUND OF THE INVENTION Thermostatically controlledelectric switches for portable heaters and the like are well known inthe art and in wide com mercial use. One such switch is shown in myprior US. Pat. No. 3,27l,546. In such switches there is provided a pairof contact blades, one of which is engaged and moved by a bimetallicblade to open and close the contacts on the blades in response totemperature changes. In order to control the temperature at which thebimetallic blade will effect contact opening or closing an adjustableinsulating pin is disposed in engagement with one of the contact bladesto vary the spacing between the contacts.

Positive on-off conditions for such switches are provided by twodifferent types of structures. In one such structure, a separate on-offswitch is electrically connected to the thermostatic switch. This is arelatively expensive structure, however, since it requires a separateswitch with its attendant expense in manufacture, mounting and wiring.In the other structure conventionally used, the insulating pin is movedby the temperature control member to move the blades into extremerelative positions such that the bimetallic blade is renderedineffective to cause contact closing or opening. This means that theswitch can not be moved to its on or off position without changing thethermostat setting.

It is an object of this invention to provide an improved electric switchwhich will overcome these disadvantages by the provision of an electricswitch which will have a thermostatic control capability but which willalso provide an on-off control without the necessity of providing anyadditional separate switch means or require a change in the thermostatsetting.

SUMMARY OF THE INVENTION In accordance with one form of the invention,first and second blades provided with first and second contacts aremounted on an insulating base. A bimetallic blade is also mounted onsaid base and is engageable with said first blade to vary the positionof the contacts with respect to each other in response to temperaturechanges.

A rigid arm is mounted on the base and supports an adjustable sleeveprovided with an insulating pin engageable with said second blade toadjust the relative positioning of the contacts and provide calibratedadjustment of the temperature of actuation of the contacts by thebimetallic blade. A cam is adjustably mounted on said sleeve inengagement with said pin. Said cam is adapted to move the pin relativeto the sleeve between an off position in which it causes said pin tomove the second blade into a position in which the contacts cannot closeand an on position in which said pin disposes said second blade in aposition in which said bimetallic blade can effect contact closing andopening in response to temperature change.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustratethe invention. In such drawings:

FIG. 1 is a side elevation of an electric switch embodying theinvention;

FIG. 2 is a fragmentary horizontal section taken on the line 2--2 ofFIG. 1;

FIG. 3 is a fragmentary vertical section taken on the line 3-- 3 of FIG.2; and

FIG. 4 is a front elevation of the control knob shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in thedrawings, the switch comprises a base formed from a plurality ofinsulating blocks 12 held in a stacked position by a bolt 14. First andsecond resilient contact blades 15 and 16 have one of their ends mountedon the base 10 and separated by one of the blocks 12 to electricallyinsulate them from each other. Desirably, terminals 17 and 18 aremounted on the blades for connecting them to appropriate electricalleads. The blades project outwardly from the base and contacts 20 and 21are mounted on blades 15 and 16, respectively, adjacent their endsremote from said base. The blades, due to their inherent resiliency, areurged toward each other toward a contact closing position. A bimetallicblade 22, electrically insulated from blade 16 by one of the blocks 12,is also mounted on the base 10. The outer end of blade 22 is bent toengage blade 15 for thus causing the contacts 20 and 21 to be moved intoand out of engagement with each other in response to temperaturechanges.

A rigid arm 24 is mounted on the base 10 in an insulated position fromblade 15 by one of the blocks 12. Conveniently, said arm may be providedwith wings 26 for mounting it in a heater or other structure. A threadedboss 28 is mounted on the arm for the reception of an adjusting sleeve30. As shown, an insulating pin 32 is slidably mounted in sleeve 30 andprojects outwardly from the inner end thereof through an opening 33 inblade 15 and into engagement with blade 16. Conveniently, the blade 16may be dented, as at 35, for locating the pin 32 against said blade.

As best shown in FIGS. 2 and 3, the outer end of the sleeve 30 isbifurcated to form a longitudinally extending slot 38 extending inwardlyfrom the outer end of said sleeve. A cam 40 is swingably mounted in theslot 38 by a pin 42 and comprises a cam nose 43 and an arm 44 projectingoutwardly from the outer bifurcated end of the sleeve. The pin 32 isheld in operative engagement with the cam nose 43 by the inherentresilien' cy of the blade 16. In this manner, the pin 32 is moved towardand away from the blade 16 during rotational adjustment of the sleevefor varying the spacing between the contacts 20 and 21. It is alsomovable with respect to said sleeve by the cam to move the blade 16 intoan off position in which the contacts 20 and 21 can not close and intoan on position in which said contacts can open and close in response tomovement of the bimetallic blade 22.

A control knob 45 is mounted on the bifurcated end of the sleeve tofacilitate the rotational adjustment of said sleeve. As shown, said knobcomprises an inner collar 46 received around the sleeve end andinterconnected by an annular web 47 to an outer collar 48. A face plate49 is seated within the collar 48 and extends over the web 47. The camarm 44 projects outwardly through the collar 46 and is slidably guidedin an elongated slot 50 formed in the face plate 49.

The control knob may be rotated in front of suitable indicia on thedevice upon which the switch in mounted to thus provide calibratedadjustment of the temperature of actuation of the contacts 20 and 21 bythe bimetallic blade 22. Conveniently, a finger 52 is struck outwardlyfrom the arm 24 in the path of rotation of a lug 54 mounted on thesleeve 30 to limit rotational movement of said sleeve and thus limit thepositioning of contact 21 with respect to contact 20 upon rotation ofsaid sleeve. The finger 52 also carries a loop spring 53 bindinglyembracing the sleeve 30 for frictionally retarding rotation of saidsleeve and thereby serving to hold the sleeve in the desired position ofadjustment.

In the operation of the switch, the cam arm 44 is moved into itsdownward position as shown in FIG. 3 thereby permitting the pin 32 toslide in the sleeve 30 under the biasing of blade 16 into an on positionin which the contacts 20 and 21 are spaced from each other by a distancewhich will permit them to open and close upon movement of the bimetallicblade 22 in response to temperature changes. The temperature at whichthe contacts will open and close in response to movement of thebimetallic blade 22 is controlled by rotation of the sleeve 30 to causethe pin 32 to move the blade 16 into the desired spacing with respect tothe blade 15. When it is desired to open the switch so that it will notclose irrespective of the movements of the blade 22, the cam arm 44 ismoved upwardly as viewed in FIG. 3 to cause the cam nose 43 to slide pin32 inwardly with respect to the sleeve 30 and move the blade 16 into anoff position such that its contact 21 will be spaced from contact 20 toprevent the closing of said contacts.

It is to be understood, of course, that if desired, the switch may alsohave employed with it a tip-over pendulum assembly such as is shown inmy aforementioned US. Pat. No. 3,271,546.

I claim:

1. An electric switch, comprising a base, first and second bladesmounted on said base and having a pair of contacts mounted thereon, abimetallic blade mounted on said base and engageable with one of saidfirst and second blades to vary the position of said contacts withrespect to each other, a rigid arm mounted on said base, a sleeveadjustably movable on said arm, a pin of insulating material slidablycarried in said sleeve and projecting outwardly from one end thereof forengagement with one of said and second blades to vary theposition of thecontacts with each other upon adjustment of said sleeve, and a cammounted on said sleeve and engageable with said pin to move said pin tocause it to move one of said first and second blades to vary theposition of the contacts with respect to each other irrespective of theadjusting movements of the sleeve.

2. The invention as set forth in claim 1 with the addition that saidsleeve has a control knob mounted on its end opposite said pin and saidcam projects outwardly from said sleeve through said knob.

3. The invention as set forth in claim 1 in which said first and secondblades are spring-biased toward each other, and the spring tension onthe blade engageable with the pin holds said pin in engagement with saidcam.

4. An electric switch, comprising a base, first and second bladesmounted on said base and having a pair of contacts mounted thereon, abimetallic blade mounted on said base and engageable with one of saidfirst and second blades to vary the position of said contacts withrespect to each other, a rigid arm mounted on said base, a sleeveadjustably movable on said arm, a pin of insulating material slidablycarried in said sleeve and projecting outwardly from one end thereof forengagement with one of said first and second blades to vary the positionof the contacts with each other upon adjustment of said sleeve, the endof the sleeve opposite its said one end being bifurcated, a control knobmounted on the bifurcated sleeve end, and a cam swingably mounted insaid bifurcated sleeve end having a cam nose engageable with said pinand an arm projecting outwardly through said control knob, said cambeing swingable to move said pin to cause it to move one of said firstand and second blades to vary the position of the contacts with respectto each other irrespective of the adjusting movements of the sleeve.

5. The invention as set forth in claim 4 in which said control knob hasan elongated slot formed therein, and said cam arm is slidably carriedin said slot.

6. An electric switch, comprising a base, first and second bladesmounted on said base and having a pair of contacts mounted thereon, abimetallic blade mounted on said base and engageable with one of saidfirst and second blades to vary the position of said contacts withrespect to each other, a rigid arm mounted on said base, a sleeveadjustably movable on said arm, a pin of insulating material slidablycarried in said sleeve and movable with and with respect to said sleeve,said pin being engageable with one of said first and second blades tovary the position of said contacts with respect to each other uponmovement of said pin with and with respect to said sleeve, and meansprojecting outwardly from said sleeve and engaging said pin for slidingpin outwardly with respect to said sleeve toward said first or secondblade engaging said pin, said first or second blade said pin urging saidpin into engagement with said means whereby said pin is releasablyretained in position with respect to said sleeve by said means and saidfirst or second blade engaging said pin.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,617,973 Dated November 2. 1971 Inventofls) Amos E. Chestnut (AssigneeArvin Industr1es,Inc.)

It is certified that error appears in the above-identified patent andthat said Letters Patent are hereby corrected as shown below:

Column 2, line 50 "in" should be --is-- Column 3, claim 1, line 16,after "said" insert --first-- Column 4, claim 6, line 29 after "sliding"insert --said-- Column 2, line 74 "upwardly" should be "downwardly".

Signed and sealed this 2nd day of May 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

1. An electric switch, comprising a base, first and second bladesmounted on said base and having a pair of contacts mounted thereon, abimetallic blade mounted on said base and engageable with one of saidfirst and second blades to vary the position of said contacts withrespect to each other, a rigid arm mounted on said base, a sleeveadjustably movable on said arm, a pin of insulating material slidablycarried in said sleeve and projecting outwardly from one end thereof forengagement with one of said and second blades to vary the position ofthe contacts with each other upon adjustment of said sleeve, and a cammounted on said sleeve and engageable with said pin to move said pin tocause it to move one of said first and second blades to vary theposition of the contacts with respect to each other irrespective of theadjusting movements of the sleeve.
 2. The invention as set forth inclaim 1 with the addition that said sleeve has a control knob mounted onits end opposite said pin and said cam projects outwardly from saidsleeve through said knob.
 3. The invention as set forth in claim 1 inwhich said first and second blades are spring-biased toward each other,and the spring tension on the blade engageable with the pin holds saidpin in engagement with said cam.
 4. An electric switch, comprising abase, first and second blades mounted on said base and having a pair ofcontacts mounted thereon, a bimetallic blade mounted on said base andengageable with one of said first and second blades to vary the positionof said contacts with respect to each other, a rigid arm mounted on saidbase, a sleeve adjustably movable on said arm, a pin of insulatingmaterial slidably carried in said sleeve and projecting outwardly fromone end thereof for engagement with one of said first and second bladesto vary the position of the contacts with each other upon adjustment ofsaid sleeve, the end of the sleeve opposite its said one end beingbifurcated, a control knob mounted on the bifurcated sleeve end, and acam swingably mounted in said bifurcated sleeve end having a cam noseengageable with said pin and an arm projecting outwardly through saidcontrol knob, said cam being swingable to move said pin to cause it tomove one of said first and and second blades to vary the position of thecontacts with rEspect to each other irrespective of the adjustingmovements of the sleeve.
 5. The invention as set forth in claim 4 inwhich said control knob has an elongated slot formed therein, and saidcam arm is slidably carried in said slot.
 6. An electric switch,comprising a base, first and second blades mounted on said base andhaving a pair of contacts mounted thereon, a bimetallic blade mounted onsaid base and engageable with one of said first and second blades tovary the position of said contacts with respect to each other, a rigidarm mounted on said base, a sleeve adjustably movable on said arm, a pinof insulating material slidably carried in said sleeve and movable withand with respect to said sleeve, said pin being engageable with one ofsaid first and second blades to vary the position of said contacts withrespect to each other upon movement of said pin with and with respect tosaid sleeve, and means projecting outwardly from said sleeve andengaging said pin for sliding pin outwardly with respect to said sleevetoward said first or second blade engaging said pin, said first orsecond blade said pin urging said pin into engagement with said meanswhereby said pin is releasably retained in position with respect to saidsleeve by said means and said first or second blade engaging said pin.